US2058527A - Process and apparatus for the manufacture of artificial materials - Google Patents

Description

W. I. TAYLOR Oct. 27, 1936.

PROCESS AND APPARATUS FOR THE MANUFACTURE OF ARTIFICIAL MATERIALS Filed Feb. 27, 1953 \wIevAM mum WW3 Patented Oct. 27, 1936 PATENT OFFICE PROCESS AND APPARATUSFOR, THE MAN- UFACTURE. OF ARTIFICIAL MATERIALS William Ivan Taylor, Spondon, near Derby, England, assignor to Celanese Corporation of America, a corporation of Delaware Application February 27, 1933, Serial No. 658,711 In Great Britain March 12, 1932 12 Claims.

The invention relates to the production of artificial filaments or the like by the extrusion of a spinning solution into a setting medium and more particularly to the production of such materials by the dry or evaporative method, that is by the extrusion of a spinning solution in a volatile solvent liquid into an evaporative atmosphere. The invention is concerned with the heating of the spinning solution prior to its extrusion, the object of the invention being to employ a gaseous medium for the purpose of applying heat to the spinning solution.

In the dry or evaporative method of spinning, a spinning jet arranged at one end of a spinning cell is adapted to direct the filaments into the cell, the cell being provided with means for bringing the evaporative medium, usually air, within the cell to the required temperature to bring about setting of the filaments. This air is usually caused to flow in counter-current direction to the filaments, that is, the air enters at or near the end of the cell remote from the jet and is drawn from the cell near the jet, the flow being induced by suction applied at the outlet for the air. The flow of air removes the volatile solvent from the filaments, solvent vapours being carried from the cell together with the air by the applied suction. i

The spinning solution is led to the jet by a pipe connected to a pump outside the cell, and this pipe, being in the neighbourhood of the outlet of the air from the cell, comes under the influence of the temperature of this air. Generally, the pipe is constituted by a filter immediately connected to the jet, and the relatively slow passage of the spinning solution through the filter increases the opportunity for the solution to be infiuenced by the surrounding air.

According to the invention the supply pipe for the spinning solution is caused to pass through a zone of evaporative medium which is hotter than that into which the filaments are extruded from the jet. In order tomaintain the temperature of the zone round the jet substantially unaffected by the presence of the hotter atmosphere round thesupply pipe, insulating means are preferably provided which wholly or partially separate the jet zone from the hotter zone. Conveniently the relatively hot air in the zone of the supply means is drawn from the main body of the cell. Special heating means may be used to raise some of .the air inthe cell to the higher temperature required or use may be made of the disposition of the cell heating means to effect a differential heating of the air, whether or ,not

the influence of the hotter air.

special heating means are used. Thus, for example, in spinning downwardly from a jet arranged at the top of a spinning cell, the heat applied to bring the air in the cell to the required temperature also serves to carry air up the cell by reason of convection. This heat is applied ator near the sides of the cell bymeans of jackets, or horizontal banks of pipes arranged along the front and back walls of the cell, and it results therefrom that the air close to the wall of the cell is more highly heated than that atthe centre of the cell. Consequently there is a tendency for the air at the sides of the cellto rise upwardly through the cell at a greater rate than the air at the centre.

Thiswhotter and more rapidly rising air may be directed intothe vicinity of the pipe supplying spinning solution to the jet near the top of the cell, the jet however being insulated from the action of this air. By the provision of a shield, which directs the hotter air to the vicinity of the filter, while allowing the relatively cooler air at the centre of the cell to pass to the vicinity of the spinning jet, the spinning solution can be brought to a higher temperature. This shield may take. the form of a perforated plate, the plate having an aperture substantially co-axial with the jet for the passage of the cooler air in the cell, and a further aperture or apertures near the wall or walls of the cell where the hotter air is rising, so that this hotter air passes to the upper end of the cell without passing through the jet vicinity. This plate may be provided with directing means which divert the hotter air on to the walls of the filter, so as to make use of its heating efiect. A further device consists of a tubular shield, again substantially co-axial to the jet, ofiering as before a passage for the relatively cooler air to the jet vicinity, and a surrounding passage for the hotter air. Conveniently this tube is supported by a perforated plate having apertures for the passage of the hotter air and it may be provided with directing means for this air to guide the air on to the filter. The shields as above described may be'made from or provided with insulating material so as to insulate the jet from For example the tubular shield may be surrounded with asbestos or similar lagging material. Again if desired the principle of the invention 5U maybe carried into effect by injecting relatively .the filter. to the filter body may be withdrawn from this .45 .f

ing the filter, or a separate outlet may be provided for this purpose. .shield may be so arranged as to cut off entirely ciently to lower its temperature to that of the air in the spinning zone. Such current of relatively cool air may be injected into the spinning zone by any desired means; for example a part of the spinning cell may be separated from the main body of the spinning cell and a current of air be passed therethrough by any desired means and subsequently injected into the spinning zone, means being adopted to ensure that the said injected air is at a lower temperature than the main body of air in the spinning cell and it not, subsequently to its passage through its spinning zone, allowed to contact with the filter candle or other supply means. Furthermore a pipe, separate but inside the spinning cell, may be similarly employed for thepurpose of injecting relatively cool air into the spinning zone.

The air supplied to the spinning zone may be derived either from cooler parts of thespinning cell itself or may be derived from the outer air orair exterior to the spinning cell. Suitable regulating means may be provided in connection with the pipe supplying the air to enable the amount of air passing through the pipe to be regulated at willand moreover to be regulated in accordance with the type of product which is to be spun, for example the solid or hollow .type of filament, and with the denier of the product- The difierential heating power of the relatively hotter and cooler'bodies of air may be more closely confined to the filter and jet respectively by suitable disposition of the outlet for the air from the cell. Thus this outlet may be disposed adjacent to the jet, or in the region between the jet and the lower end of the filter body, or even somewhat beyond the jet on the side remote from the filter, so that the relatively cooler air which has passed to the jet vicinity whether from the body' of the cell, or by injection into such vicinity, may be withdrawn from the cell without coming into contact with The hot air which is being directed same outlet, passing downwardly after encounter- In the latter case a the filter body from the influence of the air which is directed to the jet vicinity. For example, the shield may be in the form of a hood closely surrounding the supply pipe between the filter and the jet and extending downwardly to about the jet level, or if desired, to some distance below this level, and the outlet of the pipe may be connected to this hood so as to draw off all the air which has been directed to the jet. A

separate outlet is provided for the hotter air and such outlet may be arranged so as to direct the air closely towards the filter. For example,

this outlet may be in the form of a perforated plate or pipe surrounding the filter body, preferably at or near its upper end, so that the hotter air which is being directed into the zone of the filter is carried closely along the filter wall.

. '-"It is not of course necessary completely to prevent contact of the cooler air with the candle filter or other carrying means for the spinning :solution, since if desired such cooler air may contactwith the one portion of the filter candle or othersupply means so as to provide a preliminary heating, and the remainder of the filter candle or othersupply means nearer to the spinning -jet may then besubjected. to t e actio to constrain the air in the manner above indicated so as to provide the maximum heating effect on the filter. Thus where hoods are used to prevent air in the jet vicinity contacting with the filter body, the two hoods of adjacent jets maybe connected to a common pipe through which the air is drawn from the cell.

In order to separate more efiectively the hotter air from the relatively cooler air, partition plates may be carried down the interior of the cell, for example to about the level of the banks of heating pipes, where such are employed, so that the hotter air passes between these partitions and the walls and only emerges above the shields, while the relatively cooler air passes on the inside of the partition plates. These plates may if desired form part of the shields themselves.

Special heating means may be arranged for the air which is to be led to the filter. Such means conveniently comprise a coil or bank of pipes or the like separated by insulation from the jet zone and adapted to heat the air which is diverted from going into the jet vicinity. Thus, the heating means may be arranged outside a hood or funnel made of or provided with insulating material and surrounding the jet, so that the air passing outside the hood or funnel is heated before being directed to the filter. Such hood may, if desired, completely embrace the lower end of the filter, in the manner described in U. S. application S. No. 561,442 filed September 5th, 1931, and may be fitted with a draw-off device which enables the quantity of air passing to the jet vicinity to be easily regulated. Special heating means as just described may serve to enhance the flow of air induced by convection in a vertical cell. They may, however, serve as the principal means of effecting differential heating, for example in cells in which the supply of heat to the air is not adapted toproduce convection currents of hotter air which can be directed to the filter. Further, the flow of the hotter air to- Wards the filter may be induced by the suction applied to withdraw air from the cell by suitable disposition of the draw-01f device or devices. Thus, for example, air may be caused to flow outside the jet vicinity by means of a separate drawoff device or by a suitable arrangement of a single draw-off device with respect to the insulating shield, and this air may be drawn over special heating means which bring it to a higher temperature. Such an arrangement does not depend on convection to produce the flow of hotter air to the filter.

If desired the shields may be arranged to form an insulating zone between the hotter part of the cell in which the spinning solution is heated and the zone containing the jet. Thus, for example,

' two parallel plates may be arranged, one beyond level, or if desired one plate may be fitted closely around the base of the filter body so as to preclude air from passing the jet to the zone containing the filter, and in such a case a separate draw-off may be provided for the air which has passed to the filter. Preferably these plates are made from or provided with insulating material such as sheet asbestos.

It will be understood that even where the filters are not accommodated inside the spinning cell, a similar heating eifect can be obtained by the provision of a supply pipe to the spinning jet with a sufiicient capacity for heat reception. Thus, for example, the solution may be led through a pipe of large diameter or through a coil or other'pipe making a fairly long run within the cell before reaching the jet, and the hotter air may be directed by the shield into contact Withsuoh pipes.

The invention will now be described in greater detail with reference to the accompanying drawing, but it is to be understood that this description is given by Way of example only and is in no respect limitative.

Figures 1 to 4 show sectional side elevations of various forms of spinning cells according to the invention, and

Figure 5 shows a similar view of a further form of cell for carrying out the invention.

Referring to Fig. 1, a spinning cell I0 is provided with a pipe I I for the supply of spinning solution, the pipe I I leading the solution through a filter candle I2 to a jet I3 from which it is extruded in the form of filaments I4. The filaments I4 pass down the length of the cell I0 and are deflected out of the cell through an orifice I6 by means of a guide IS. The filaments pass round a feed roller II which conducts them to the guide I8 of a cap spinning device I9 by means of which they are twisted and Wound. Evaporative medium enters the cell through an inlet 20 and passes up the cell, being heated by means of pipes 2I through which flow steam, hot water, or other suitable heating medium.

The current of air passing up the cell I0 is therefore hotter in the neighbourhood of the pipes 2| than in the middle of the cell, and the hot air in the neighbourhood of such pipes is allowed to proceed up the cell and round the edges of a baffle plate 23 disposed horizontally just above the spinning jet I3. The cool air in the neighbourhood of the filaments I4 however is checked by the baffle plate and so prevents the hot air from coming into the middle of the cell. This cool air is removed by means of a draw-oil pipe 24 provided with a calibrated disc orifice 25 which controls the rate at which the medium is so withdrawn. The pipe 24 conducts the evaporative medium drawn off to a header 26. The hot evaporative medium passing round the edges of the baffle plate 23 comes into contact with the filter candle I2 and has the effect of heating the spinning solution passing through the filter can dle by heat exchange through the walls of the candle. A second baflle plate 21 is provided just above the candle I2 in order to ensure that this hot air passes in the neighbourhood of the upper part of the candle I2 and supply pipe I I. A second draw-ofi pipe 28 having calibrated disc orifice 29 is provided by means of which this evaporative medium is drawn off at a controlled rate into a header 36. The baffle plate 23 is made of sheet asbestos or other insulating sheet material, so that the heat of the air about the filter candle 12- is" not communicated to the cool air about the jet I3.

In Figure 2 only the upper part of the cell is shown. The cool air passing up the middle of the cell is brought into the neighbourhood of the jet I3 by meansof a suitably'shaped insulating curtain 32 surrounding the jet, and is drawn 01? through the space within the curtain 32 by means of draw-off devices 24, 25. The hot air in the neighbourhood of the heating pipes 2I passes outside the curtain 32'and proceeds to the neighbourhood of the filter I2. The tempera ture of the air passing outside the curtain in this manner is boosted by means of additional heating pipes 33 disposed round about the candle I2. 'I'heair passing through the neighbourhood of the candle proceeds through fhe middle of the baflie 21 and is drawn oif by means of a device 28, 29 as described with reference to Figure 1. It will be seen that in this case a bafile plate 34 is provided at the top of the curtain 32 and does not completely close the space about the jet I3 so that a small quantity of cool evaporative medium may pass this way.

In Figure 3 the hot air coming from the pipes 2I is deflected on to the filter candle I2 by means of tubular cowls 36, while the cool air in the middle of the cell passes through a cone 3! leading it into the neighbourhood of the jet. Two such cowls 36 are shown in Figure 3, one to the right and one to the left of the candle I2. The cowls 36 lead the hot air directly on to the filter candle, and prevent it from entering into the corners of the cell, where some of its heat would be wasted. The mouths of the cowls 36 fit closely round the cylindrical surfaces of the candle I2, and so constrain all the hot air to pass close to the candle. The air passing through the cone 31 leaves by the top of the cone and passes to the upper part of the cell outside and between the cowls 36 so that both the hot and the cold air pass through the bafile plate 21 and are drawn off by means of the device28, 29. In this case means may if desired be provided to draw-off the cool air inside the cone '31 but since such cool air is prevented from contacting with the candle by the presence of the cowls 36'this expedient is not essential. The cowls 36 and cone 3! may be lagged with asbestos or other insulating material to prevent transference of heat by conduction from the inside of the cowls to the inside of the cone.

In Figure 4 the hot air is kept out of contact with the spinning jet I3 by means. of an inverted insulating cone 4D and is then constrained to pass through a tube 4I surrounding the candle I2 in order that it may proceed through the hole in the baflle plate 21. Draw- off devices 42, 43 are provided inside the cone 40 and at the top of the cell respectively, the rate of flow of evaporative medium through these draw-off devices being controlled by means of valves 44, 45. The pipes 42, 43 lead to a common header 46.

In Figure 5 cool air is introduced into the neighbourhood of the jet I3 from outside by means of a pipe 41 communicating with the atmosphere. In this figure the main current of air enters the cell through the inlet 48 which is controlled by means of a calibrated disc orifice 49 and the air entering by the pipe 41 is similarly controlled by a calibrated disc orifice 50. The hot air coming from the pipes 2| is kept out of the neighbourhood of the jet I3 by the presence of the current entering by the pipe 41 and is caused to pass in the neighbourhood of the filter 484,788 filed September 27th, 1930.

candle l2 by means of baffles 52 and 21. A drawoff device 24, is provided opposite the inlet pipe 41 and a second draw- off device 28, 29 is fitted in the top of the cell, these two pipes joining in a common pipe 53 in the manner described with reference to Figure 4. The filaments l4 leave the cell by an outlet 54 which is of the form described in U. S. application S. No. The outlet 54 is not substantially larger than the filaments passing through it. This prevents air from entering by the filament outlet, and enables the amount of air entering the cell to be accurately controlled by the apertures 49, 50 on the inlets 41, 48.

What I claim and Patent.is:-- 1. Process for the production of artifical filaments, which comprises extruding a spinning solution inthe form of filaments, drawing said filaments through a body of evaporative medium,

desire to secure by Letters locally heating said body of evaporative medium,

passing the solution prior to extrusion through a zone of evaporative medium which is hotter than that into which the solution is extruded,

.feeding said hotter zone with evaporative atmosphere coming directly'from'the heated localities in said body of evaporative medium, segregating the neighborhood of the point of extrusion from said zone and feeding said neighborhood with cooler evaporative medium.

2. Process for the production of artificial filaments of cellulose acetate, which comprises extruding a solution of cellulose acetate in the form of filaments, drawing said filaments through a body of evaporative medium, locally heating said body of evaporative medium, passing the solution prior to extrusion through a zone of evaporative medium which is hotter than that into which the solution is extruded, feeding said hotter zone with evaporative atmosphere coming directly from the heated localities in said body of evaporative medium, segregating the neighborhood of the point of extrusion from said zone,

"neighborhood.

3. Process for the production of artificial filaments, which comprises extruding a spinning solution in the form of filaments, drawing said filaments through a body of evaporative medium, locally heating said body of evaporative medium, passing the solution prior to extrusion through a zone of evaporative medium which is hotter than that into which the solution is extruded, feeding said hotter zone with evaporative atmosphere coming directly from the heated localities in said body of evaporative medium, further heating such evaporative atmosphere when in said hotter zone, segregating the neighborhood of the point of extrusion from said zone and feeding said neighborhood with cooler evaporative medium.

calities in said body of evaporative medium, segregating the neighborhood of the point of extrusion from said zone and feeding said neighborhood with cooler evaporative medium.

5. Process for the production of artificial filaments, which comprises extruding a spinning solution downwardly in the form of filaments, drawing said filaments downwardly through an upwardly moving body of evaporative medium, 10- cally heating said body of evaporative medium, passing the solution prior to extrusion through a zone of evaporative medium which is hotter than that into which the solution is extruded, feeding said hotter zone with evaporative atmosphere coming directly from the heated localities in said body of evaporative medium, segregating the neighborhood of the point of extrusion from said zone, feeding said neighborhood with cooler evaporative medium and withdrawing evaporative medium separately from said zone and from said neighborhood.

6. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in said cell, means for supplying spinning solution to said jet, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, means for segregating the neighborhood of the spinning jet from said zone and means for conducting cooler evaporative medium into said neighborhood.

'7. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in said cell, means for supplying spinning solution to said jet, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, heat insulating means for segregating the n-eighborhood of the spinning jet from said zone and means for conducting cooler evaporative medium into said neighborhood.

8. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in said cell, means for supply spinning solution to said jet, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, means for segregating the neighborhood of the spinning jet from said zone, means for conducting cooler evaporative medium into said neighborhood and means for withdrawing evaporative medium from said zone and said neighborhood.

9. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in said cell, means for supplying spinning solution to said jet, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, means for segregating the neighborhood of the spinning jet from said zone, means for conducting cooler evaporative medium into said neighborhood and separate means for withdrawing evaporative medium from said zone and said neighborhood.

10. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in said cell, means for supplying spinning solution to said jet, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, heating means contained in said zone, means for segregating the neighborhood of the spinning jet from said zone and means for conducting cooler evaporative medium into said neighborhood.

11. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in the upper part of said cell, means for supplying spinning solution to said jet, means in the lower part of said cell for introducing evaporative medium thereto, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, means for segregating the neighborhood of the spinning jet from said zone and means for conducting cooler evaporative medium into said neighborhood.

12. Apparatus for the production of artificial filaments, comprising a spinning cell adapted to contain a body of evaporative medium, a spinning jet in the upper part of said cell, means for supplying spinning solution to said jet, means in the lower part of said cell for introducing evaporative medium thereto, means for heating locally the body of evaporative medium in said cell, means for conducting evaporative medium directly from said heating means to a zone surrounding said supply means, means for segregating the neighborhood of the spinning jet from said zone, means for conducting cooler evaporative medium into said neighborhood and separate means for withdrawing evaporative medium from said zone and said neighborhood.

WILLIAM IVAN TAYLOR.

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